[erlang-bugs] Guard clauses using not, binaries and andalso blows up the compiler chain

José Valim <>
Sat Oct 27 12:16:40 CEST 2012

Hello everyone,

The following function cannot compile on Erlang R15B02:

    format(Datetime, << H, T / binary >>) when not ((H >= $a) andalso (H =<
$z)) andalso
        not ((H >= $A) andalso (H =< $Z)) ->
      { Datetime, T }.

Here is a snippet of the failure:

format_test.erl:none: internal error in v3_codegen;
crash reason: {{case_clause,


I believe the current code to be valid Erlang and it should not blow up the
compiler chain. :)
Furthermore, simply adding other clauses to this function (without touching
it) makes the error go away.

I have put more information about the failure and a full sample module in a
gist: https://gist.github.com/dd4c1240a1510711b26a
I tried to further debug the issue, but I could not pinpoint exactly the
failure. Let me know if I can help any further.

Thanks for your time,

PS: I have sent this same e-mail one week ago but it didn't appear on the
erlang-bugs mailing list. So I am sending it again. Apologies if it appears

José Valim
Founder and Lead Developer
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